ELECTROCHEMICAL REMOVAL OF HEXAVALENT CHROMIUM BY ELECTROCOAGULATION: COMPARATIVE STUDY OF BATCH AND CONTINUOUS REACTOR PERFORMANCE

This study explores the effectiveness of electrocoagulation (EC) for removing toxic hexavalent chromium (Cr(VI)) from industrial wastewater using iron and aluminum electrodes in both batch and continuous modes. Iron electrodes demonstrated superior performance, achieving up to 99.8% Cr(VI) removal in batch mode at an optimal current density of 5 mA/cm2, while continuous operation at 50 L/h achieved comparable removal after 30 minutes, with slightly lower efficiency due to reduced retention time. The lowest specific energy consumption (2.82 kWh/kg Cr(VI)) was also recorded under these optimal conditions, highlighting economic feasibility. Fourier-transform infrared (FTIR) analysis of the sludge confirmed the reduction of Cr(VI) to the less toxic Cr(III), primarily in the form of Cr(OH)3. Characteristic peaks indicate Cr-O vibrations in chromium hydroxide, while the presence of hydroxyl (-OH) groups confirms the formation of iron hydroxide complexes that facilitate Cr(VI) adsorption and precipitation. Additional spectral features suggest the presence of iron oxides, further supporting the electrocoagulation mechanism involving the generation of coagulant species in situ. Overall, the results affirm EC as a highly efficient and cost-effective treatment method, particularly suitable for large-scale applications.